PResponsive

This plugin will add a image below your posts, allowing your visitors to share your posts with their friends, on FaceBook, Pinterest, Google+, Twitter, Myspace, Friendfeed, Technorati, del.icio.us, Digg, Google, StumbleUpon, and other. After plugin is activated a buttons will appear after the content of the post.Clicking this button will bring the user to the bookmarking site. If the user isn’t logged in they will be prompted to do so. 
Post your articles to the social bookmarking sites and get traffic.

WP Social Bookmarking

WP Social Bookmarking plugin syndicates your blog posts in social networking sites.

innocuo

Admin Starred Posts lets you mark posts, pages and custom posts within the WordPress admin with stars. 
This helps you highlight a post, or mark it so you remember is important.
For example, you might have tons of pages, but are always editing one or two. In that case, star those pages, 
and they’ll be easily recognizable in your list of posts.
If you’ve used Gmail before, you’re very familiar with this feature. Similar to that email client, this plugin 
let’s you click on a star in your list of posts, pages and custom posts to ‘star’ it.
The plugin works out of the box, but you also get some configuration options to help you customize it to your workflow.
Configuration Options
<ul>
<li>Rotate between 12 different “stars”</li>
<li>Drag and set the orders of your stars</li>
<li>Enable/disable this feature for any post type in your WordPress install</li>
<li>Decide whether you want stars to be visible to every one, or in a per user basis.</li>
</ul>
Other Features
<ul>
<li>You can display only starred posts by using the “Stars” filter available at the top of the posts list.</li>
</ul>
This plugin requires WordPress 3.8 or higher

Admin Starred Posts

Nicely does the job of marking like email inbox. Some feature enhancements like adding from post edit page with a note will be great. 

Excellent plugin


This plugin is so useful for managing site wide updates and status of pages especially when working with a group- which are done, which need attention, which haven't been started. I install it on every site I've ever worked on, so I'm probably responsible for at least a hundred of the active installations. Please keep it updated and tested!!


I absolutely love this plugin!

Mark posts, pages and custom posts in your WordPress admin; pretty similar to the stars feature in Gmail.

WP Social Bookmarking vs Admin Starred Posts